Endocrine Abstracts

Articular cartilage maintenance and repair is regulated by numerous endocrine and paracrine factors. Investigation of molecular mechanisms underlying osteoarthritis (OA) is limited by inability to identify early stage disease and individuals at risk of progression. Susceptibility to OA is genetically determined and the availability of mice from the International Knockout Mouse Consortium with deletions of every known gene provides a unique opportunity to investigate its pathophysiology. Nevertheless, screening for joint abnormalities using standardized Osteoarthritis Research Society International (OARSI) histology protocols is labour intensive and costly, thus limiting progress. We hypothesize that the triiodide ion in Lugol’s iodine solution penetrates the intact joint to provide excellent contrast resolution and permit simultaneous imaging of unmineralized and mineralized tissues. The aim of this study was to investigate triiodide staining in knee and hip joints from WT mice to determine morphological and structural parameters of articular cartilage and subchondral bone.

Limbs from WT mice were fixed and stored in isotonic 70% ethanol and images of knee and hip joints obtained using digital x-ray microradiography. To determine the optimal osmolality and triiodide concentration, samples were placed in varying dilutions of Lugol’s iodine solution. To investigate the optimal duration of staining and X-ray intensity required, samples were imaged between 24 and 144 h using accelerating voltages of 16–35 kV. Staining for 48 h in a 25% saturated solution of Lugol’s iodine (308 mOsmol/l) achieved excellent soft tissue contrast at 31 kV and 19 s exposure and resulted in no demonstrable tissue shrinkage.

These studies demonstrated that triiodide staining results in excellent visualization of the joint capsule, menisci, articular cartilage and mineralized tissue establishing that this method can be used for high resolution three-dimensional imaging using micro-CT and electron microscopy.

This strategy provides a novel approach for high throughput detection of early joint disease in genetically modified mice.

Declaration of funding: Yes.

Details: This work was supported by the Wellcome Trust (grant number 94134/Z/10/Z).

DOI: 10.1530/endoabs.31.P10